Systematic Reviews

What is systematic review?

- Well documented of intervention research

- Scientific methodology- reduced systematic errors (biases)- reduced random errors (by chance)

- Provide more objective, comprehensive view

1. Health personnel need updated information

2. Textbooks are out of date

3. Too much information (good and bad)

4. Journals are disorganized and limited

5. Knowledge and performance deteriorate

Why are systematic reviews important?

Advantages of systematic reviews

• Inform clinical decision making

- provide strong evidence regarding benefits or harms of a particular intervention

• Highlight area requiring further primary research

What’s different about a systematic review?

Traditional

• methodology not transparent

• different reviewers reach conclusions

• become out of date may not be comprehensive or accurate

Systematic

• designed to minimise bias

• explicit and reproducible methodology

• regularly updated (Cochrane)

• aim to be comprehensive and reliable

Key features of a systematic review

• clearly stated objectives• pre-defined eligibility criteria• explicit, reproducible methodology• a systematic research• an assessment of the validity of the findings of

the included studies• systematic presentation and synthesis of the

findings of the included studies

Research synthesis

• Systemic reviews

• ± Meta-analysis

Step in conducting a research synthesis

1. Formulate review question2. Define inclusion and exclusion criteria (studies,

participants and outcomes)3. Locate studies4. Select studies5. Assess study quality6. Extract data7. Analyze and present results8. Interpret results

Question: specify a clearly focus

• Population (group to whom the intervention will apply)

• Intervention (the therapy, treatment or preventive policy to be carried out)

• Comparison (what will the intervention be compared against; alternative intervention vs. placebo or no intervention

• Outcomes (what to measure, what is important)

Example

To assess the effectiveness of interventions (which may include placebo or no treatment) for the

treatment of oral mucositis, or its associated pain, for patients with cancer receiving chemotherapy and/or

radiotherapy

population

comparison

intervention

Outcomes: mucosotis at different levels of severity, oral pain scores, amount of analgesia, stay in hospital (days), cost of oral care etc.

Study design: only randomized, controlled trials were eligible for the review

Quality

Bias

• selection bias (non random differences between the people)

• attrition bias (more participants drop out of one arm of experiment)

• performance bias (those receiving intervention are aware)

• detection bias (assessing outcomes are aware)

Search strategy

• several electronic databases (including the Cochrane Library)

• check through the reference lists of included studies

• relevant reviews

• letter to relevant pharmaceutical companies

• experts in the field asking about unpublished or ongoing work

• hand searching of relevant journals or conference abstracts

• translation of foreign-language articles

Quality assessment

Data extraction

Undertaken independently by two reviewers

Quality of Evidence

Ia. Research synthesis of randomized controlled trial (RCT)

Ib. At least one properly designed RCTIIa. At least one well designed controlled

without randomizationIIb. At least one well-designed cohort studyIII. Evidence obtained from case control or

descriptive studiesIV. Opinion of respected

Critically appraising review

1. What are the review’s objectives? Well defined questions (population, intervention/control, outcomes)

2. How comprehensive was the search strategy? Effort to search

3. What were the inclusion/exclusion criteria? Clearly stated and appropriate

4. How was the validity of the primary studies assessed?

5. How were data extracted from the primary studies?

6. Are the characteristics of the included studies clearly displayed? A table showing the study characteristics of each included primary study

7. Does the review examine difference/similarities between the included studies and their results? Check heterogeneity between studies

8. What the synthesis of the data carried out appropriately? Whether the data pooled qualitatively or statistically

9. Were the results interpreted appropriately? Any conclusions, implications for research or practice should follow on logically from the results.

Where can find systematic review?

• The Cochrane Database of Systematic Reviews (CDSR)

• The Database of Abstracts of Reviews of Effectiveness (DARE) produced by the NHS Centre for Reviews and Dissemination (CRD)

How to prepare Cochrane protocol

Rationale for protocols

• Minimize the potential for bias in the review process

• Promotes transparency of methods and processes

• Reduces the potential for duplication

• Allows peer review of the planned methods

• Protocols for Cochrane reviews are published before the completed systematic review in the Cochrane Database of

Systematic Reviews (CDSR)

Format of a Cochrane review

• Easy to find the results of research assess the validity, applicability and implications of those results.

• Guide the review authors to report their work explicitly and concisely and minimizing the effort required.

• Facilitate the electronic publication and maintenance of reviews.

Sections of a protocol for a Cochrane review• Title

• Protocol information

1. Authors

2. Contact person

3. Dates

4. What’ new

5. History

6. Background: Description of the condition, intervention, why it’s important to do this review

7. Objectives

8. Methods: criteria to select studies, search methods for identification of studies, data collection and analysis

Sections of a protocol for a Cochrane review

• Acknowledgements

• References

• Tables and figures

• Additional tables

• Figures

Sections of a Cochrane review• Title

• Review information

- Authors

- Contact person

- Dates

- What’ new

- History

• Abstract

- Background

- Objectives

- Search strategy

- Data collection and analysis

- Results

- Author’s conclusion

• Plain language summary

-Plain language title

- Summary text